This thread is intended to be a one-stop-shop for everything you've ever wanted to know about Audi I5 crankshaft cogs. Also known as crank sprocket, pulley, gear, etc.

It is well-known and documented that when doing a timing belt job on an Audi ur5pot, whether that be AAN, 3B, ADU, ABY, 7A, etc. the crankshaft cog must be replaced with a new one because the stock gear is made of sintered steel. Sintered means the material (in powdered form) is put under tremendous force and heat such that the material fuses together. This creates a part with questionable strength properties, especially when exposed to impulse loads. Using one of these stock cogs is perfectly fine when installed properly, but they should should be replaced with every timing belt service and using an impact driver to install them, without a crankshaft locking device at least, is NEVER a good idea.

Instead of buying a new one every time the timing belt is changed, why not just make a much stronger version? Well, several have done this. However, the information about these high-strength cogs is not readily-available or so far spread out that it'd be nice to be able to take a look at it all in one place. Also, when you do have the information in-hand, how do you choose which one to use? That's exactly what this thread is for!

Disadvantages: At least one user has reported that the teeth of the gear are not timed correctly with the clocking of the holes for alignment with the crank pulley. This makes setting timing and adjusting belt tension nearly impossible with a stock cam pulley. Also, the teeth are not rounded at the top like the supertorque belts are made for. This could cause premature wear on the belt. Look very closely and you will see that the edges of the teeth are angled rather than rounded. Don't let the curved front face of the gear fool you into thinking they have a curved profile.

Stock vs SPM vs Tommi's Billet

Illustration of tooth alignment problem on the Tommi's Billet

CWG RacingMaterial: Heat treated 4340 steelConstruction: Single pieceTooth Profile: Stock teeth tops (rounded), rounded valleysPrice: $200 plus shipping. Could go lower in quantity.Availability: I could have more made if anyone wanted some, but I think there is a better option.

Advantages: Among the strongest of all gears using heat treated 4340 steel. Ground inside diameter to ensure perfect fit onto crankshaft. Top tooth profile is exactly the same as stock, rounded “super torque” style teeth. Machined dimple for crank pulley alignment. Can be made more cheaply than most of the other gears here because of the milled teeth (rather than cut by gear), although testing still needs to be done on this tooth design with respect to long term reliability and power-holding potential.

Disadvantages: *FAIL GEAR* These were made with the bolt holes for the crank damper in the wrong place due to manufacturer mistake. Production has ended since. No plans to continue production because it isn't easy to compete with the Terrybullwon gear! Valleys of teeth are rounded in order to keep cost down and allow the gear teeth to be produced by milling rather than by grinding with a special-made gear cutter or by wire EDM (both processes would generally require the gear to be made in two pieces). Whether this is a disadvantage or not is questionable. I will test this gear out on my avant for stock, long-term reliability, and may also test it on the revver if I have the balls

Advantages: According to fcarspec1 on quattroworld, it uses a separate key that slides a little deeper into the crank notch than the stock key.

Disadvantages Also according to fcarspec1, you have to do a wire transfer to their bank. Part# DBR.Z26.D64.8.CD5 and also the key is not quite in the same place as the OE part so the mark on the damper is off a little once installed, so you must time the engine with the mark on the flywheel. Teeth appear to be squared off just like the Tommi's Billet gear. This all sounds very similar to the Tommi's billet gear...

Advantages: Recommended by Jeff Gerner as the crank cog of choice due to it's build quality and especially the gear profile which matches the stock "super torque" (rounded edges on teeth rather than squared off) tooth profile. Valleys are same as stock as well. Also coated for corrosion resistance. Made by HPC gears, most likely the biggest and best gear cutters in the UK

Disadvantages: ??

Terrybullwon gear

Here you can see the separate belt guard which is pressed on

Belt wrap

SPM?

Material: Steel (???)Construction: ??Tooth Profile: ??Price ??

Advantages: ??

Disadvantages: Possibly not available. I have only seen one in this picture. Tooth design looks like it could be "off."

SPM in the middle apparently

Volcano RS from S2 Forum

Material: Steel (???) Heat treatedConstruction: 3 piece (separate key and alignment pin)Tooth Profile: Possibly rounded teeth and has rounded valleyPrice ~$108.50 plus postage from the UKAvailability: Last post on thread was in 2013. Not sure if still available http://www.s2forum.com/forum/showthread.php?t=33219

Advantages: Cheap!Comes in wider width as well for using 25 mm belt. Appears to have correct, rounded teeth.

Disadvantages: Teeth appear to be squared off and not the "super torque" style even though it is advertised as such. I could be wrong though. If so, belt wear will be accelerated.

Faheemo from S2 Forum

Material: EN19T tool steel. Some (not all) heat treated and have corrosion-resistant coating. It seems that all the latest ones were coated at least.Construction: Two piece? (undercut integral key and separate alignment pin)Tooth Profile: Teeth cut on a gear-cutting machine. Not sure if super-torque style tooth edges or notPrice $225Availability:http://www.s2forum.com/forum/showthread.php?t=32516 It seems they may not be made anymore.

Advantages: This is the gear EFIexpress use to sell. It was of good quality. The only questionable thing is the teeth, but they haven't seemed to cause any problems.

Disadvantages: No longer in production?? Appears to have sharp, squared-off edges on teeth rather than rounded.

Faheemo from S2 Forum cog

audi * line (eBay.de user)

Material: C45 steelConstruction: 4 piece (separate key, alignment pin, and belt guard)Tooth Profile: Appears to be very good. As close to stock as the Terrybullwon gear from the looks of itPrice 148 euro (approx) $163 US without shipping. Shipping is likely more than 20 eurosAvailability: eBay.de username audi * line - located in Poland - may or may not ship to US. Contact seller

Advantages: Appears to have very nice teeth in the correct profile. Seems to be well made by an experienced machinist judging from pictures.

Disadvantages: Seller may or may not ship to US.

PKM

Material: ???Construction: Appears to be very similar to Terrybullwon's gear but with separate key and rolled sheet metal pin (not a fan of these two things)Tooth Profile: Appears to be very good. As close to stock as the Terrybullwon gear from the looks of itPrice ~220-230 eurosAvailability: Autewo.de (and eBay)

Advantages: Appears to have very nice teeth in the correct profile.

Disadvantages: The separate key and rolled sheet metal pin are... cheap. It may be perfectly functional, but I prefer integral pieces and precision machining. It makes you question the quality of the rest of the gear.

Last edited by loxxrider on Tue Oct 06, 2015 1:11 pm, edited 6 times in total.

Material: EN24 SteelConstruction: 3 piece (separate belt guard and pin, but integral key)Tooth Profile: Same as stock (confirmed by Jeff Gerner)Price $155 plus shipping from UKAvailability: Currently available. Jeff should have them (contact at [url]fourringperformance.com[/url]) and also from Terrybullwon

Thanks for the write up i only sent Issam two over for him and Jeff for there motors, so no one other than my self has stock of these pulleys at the moment. The Price is lower than some my mark up is not massive i do it more for the love. I am working on a adjustable gear and this will be available late fall i hope.

A really nice bit of kit this will be i am pretty excited to get mine on my motor!

Is it really that big of a problem? The crank cog on my JT has been on and off several times with an impact gun and that was 100k+ ago... odometer reads close to 380k now.

Maybe it is just people using really weak crappy guns from Sears or Harbor Freight with only 100psi air pressure from their little pancake air compressors and the gun sits there rattling and rattling and rattling instead of just ZIP off and on?

Or is it more of a problem with being insufficiently tight because people aren't checking the torque with a torque wrench, and the harmonic damper bolts to the crank cog, and long crankshafts in high power engines make a lot of torsional vibrations working that critical junction loose. Look at the other end of the crank... eight 10mm bolts to hold the flywheel in place, and you know that isn't for the torque because the driveshaft is held on by six spindly 8mm bolts and there is torque multiplication before you get to that point.

I have long suspected the pulley itself being out of balance causing all kinds of problems. For example, I zero balanced my old 034 pulley along with the rest of the motor, with the trigger wheel welded to it, and it seems to be the only specimen to have lasted past a couple thousand miles. It's probably 30-40k and still going. I always wonder if the crank cog failures. are related to small vibrations.

Hey guys, sorry I had to bump this thread, I wondered if any of you recalls of a guy on a forum or a company making crank gears for 10V engines ( part 035105263C ) ?I'm 100% sure I saw it while wandering on a forum but I can't remember where / couldn't find it ...

Guys just a heads up another batch of the "terrybullwon" pulley will be ready in a few weeks and i am running a pre production price to soften a massive out lay. Please contact me with interest at James@jmdmotorsport.com